Silver halide photographic materials are in general materials which have a light-sensitive emulsion layer and, as required, various combinations of structural layers such as intermediate layers, protective layers, backing layers, antihalation layers and anti-static layers, for example, coated onto a support such as a synthetic resin film, paper or a paper which has been covered with a synthetic resin, or glass, for example. Silver halide photographic materials frequently exhibit pressure fogging as a result of contact between the photosensitive material and various types of apparatus used in the manufacturing of the material such as processes of coating, drying and finishing, for example, and during transport through a camera, during development processing, during printing or during projection, for example; as a result of contact friction between the photosensitive material and other materials; or as a result of contact friction between photographic materials themselves, e.g., which occurs between a photosensitive material surface and the reverse surface of a photographic material.
Methods in which polymer latexes or plasticizers such as polyhydric alcohols, for example, are included, methods in which the silver halide/gelatin ratio in the silver halide emulsion layer is reduced, methods in which the thickness of the protective layer is increased and methods in which a lubricant or colloidal silica is added to the protective layer, which alleviate pressure before the pressure reaches the silver halide grains, are well known as means of improving the variation in density which results from the application of such pressures.
For example, a method in which heterocyclic compounds are used is disclosed in British Patent 738,618, a method in which alkyl phthalates are used is disclosed in British Patent 738,637, a method in which alkyl esters are used is disclosed in British Patent 738,689, a method in which polyhydric alcohols are used is disclosed in U.S. Pat. No. 2,960,404, a method in which carboxylalkyl cellulose is used is disclosed in U.S. Pat. No. 3,121,060, a method in which paraffins and carboxylic acid salts are used is disclosed in JP-A-49-5017 and a method in which alkyl acrylates and organic acids are used is disclosed in JP-B-53-28086 (the terms "JP-A" and "JP-B" as used herein refer to a "published unexamined Japanese patent application" and an "examined Japanese patent publication", respectively).
However, methods in which plasticizers are added reduce the mechanical strength of the emulsion layer and so the amount of plasticizer which may be used is limited, and when the silver halide/gelatin ratio is reduced, development is retarded and there is the disadvantage in that the suitability for rapid processing is lost.
Furthermore, polyhydroxybenzene compounds have been introduced for various purposes into silver halide photographic materials which contain hydrazine derivatives, as is disclosed, for example, in U.S. Pat. Nos. 4,332,108, 4,385,108 and 4,377,634, and a technique for the prevention of pressure sensitization is disclosed in JP-A-62-21143.
However, in the printing industry there is a great desire for greater efficiency and increased operational speeds, and there is a wide ranging need for increased scanning speeds and shorter processing times for photosensitive materials.
In order to respond to these requirements of the printing industry, it is desirable to increase the scanning speeds in exposing devices (scanners and plotters) and to increase the number of lines and to stop down the beam in the light amount in order to improve picture quality. Thus, in connection with silver halide photographic materials, there is a need for higher photographic speeds with excellent stability and for suitability for rapid development processing.
Here, the term rapid development processing signifies processing in which the time elapsing from the entry of the leading edge of the film into an automatic processor through the development tank, the crossover part, the fixing tank, the crossover part, the water washing tank and the drying part until the leading edge of the film emerges from the drying part is from 15 to 60 seconds.
In order to provide a photosensitive material with suitability for rapid processing it is necessary to increase the rate of development and the fixing rate and to shorten the drying time, and for this the amount of gelatin which is used as a binder in the emulsion layer and the protective layer must be reduced. In particular, the thickness of the protective layer must be reduced and this results in a marked increase in pressure fogging.